GB2599360A

GB2599360A - Balancing of heating systems

Info

Publication number: GB2599360A
Application number: GB2015033.0A
Authority: GB
Inventors: Fadmy Petr; Macourek Karel; Nespurek Lukas
Original assignee: Pittway SARL
Current assignee: Pittway SARL
Priority date: 2020-09-23
Filing date: 2020-09-23
Publication date: 2022-04-06
Also published as: GB202015033D0

Abstract

A heating system 100 comprises a plurality of radiators 112,122,132 and a boiler 150 (e.g. condensing boiler). Each radiator has a respective outlet valve 116,126,136 connected to an outlet of the radiator whereby each outlet valve is configured to respond to the temperature of fluid (e.g. water temperature) at the outlet to control fluid flow rate through the outlet to bring the fluid temperature at the outlet to a target temperature. All the radiators have a mutual outlet temperature so the system is balanced to enable a common boiler return temperature. The outlet valve ideally comprises thermally responsive wax (117, figure 3) that urges a piston (118, figure 3) to reduce water flow at higher outlet water temperatures. Each outlet valve is ideally calibrated prior to connection so the target temperature is 10 to 16 degrees lower than the temperature of water leaving a condensing boiler so that the return water temperature is below the condensation temperature of the boiler, thereby ensuring boiler efficiency. Each radiator may also include a thermostatic radiator valve 114,124,134 on its inlet to control heating of a room 111,121,131 in which the radiator is located. A method and kit of parts are also claimed.

Description

BALANCING OF HEATING SYSTEMS

TECHNICAL FIELD

100011 The present disclosure concerns heating systems. More particularly, but not exclusively, this invention concerns a heating system comprising an outlet valve configured to balance the heating system. The invention also concerns a method of balancing a heating system.

BACKGROUND

poca] Conventional heating systems often include a boiler that is fluidly connected via a pipe network to a number of hot water radiators. A multitude of factors can affect the flow of water in the system: length of piping, size of radiator, fouling, number of bends, etc. All of these factors affect the pressure drop in the water (i.e. resistance to flow of the water) across parts of the system, such as the pressure drop across radiators or groups of radiators in a zone.

poo] As water will ordinarily take the path of least resistance, radiators/zones that have a lower pressure drop are susceptible to receiving too much hot water and being over-heated, while radiators/zones that have a greater pressure drop are susceptible to not receiving enough hot water and consequently being under-heated.

100041 Balancing of heating systems is necessary to avoid these problems.

100051 One way in which this is done is by static balancing. A manual outlet valve is adjusted on each fully open radiator/zone to ensure a pressure drop to create the same -2 -flow rate through all of the radiators/zones in the heating system.

100061 One draw-back of static balancing is that when one or more radiators reduces its flow rate (via a local thermostat, or manually by a user, for example), the flow-of hot water is not redistributed evenly across the other radiators in the system. This leads to over/under-heating.

100071 An alternative way in which balancing is achieved is by dynamic balancing. For dynamic balancing, a valve is included in each local radiator/zone system that responds to the pressure/flow rate of the water. An increase in pressure/flow rate causes the valve to restrict the flow, in an attempt to maintain a constant flow rate.

[mos] One problem with dynamic balancing is that although the flow rate is balanced, the temperature of the water leaving the radiator/zone still undergoes fluctuation -particularly if specific radiators/zones in the system are adjusted independently. Condensing boilers utilise the flue gases of the boiler to heat up the water returning from the heating system back to the boiler. Higher water return temperatures can reduce the efficiency of such a system.

100091 Embodiments of the present invention seek to mitigate the above-mentioned problems. Alternatively or additionally, the present invention seeks to provide an improved heating system.

SUMMARY OF THE INVENTION

100101 The present invention provides, according to a first aspect, a heating system comprising a plurality of fluid filled radiators. Each radiator comprises an inlet and an outlet. An outlet valve is connected to each of the outlets. -3 -

The heating system also comprises a boiler fluidly connected to the plurality of radiators. Each outlet valve is configured to respond the temperature of the fluid at the outlet. Each outlet valve also controls the flow of fluid through the outlet to bring the temperature of the fluid at the outlet to a predetermined target temperature. The outlet valve controls the flow such that there is a common outlet temperature for all of the radiators, thereby balancing the system and enabling a common boiler return temperature.

poll] Having a common boiler return temperature is advantageous as the amount of heat provided throughout the system is distributed evenly. In addition, where a condensing boiler is used as the energy source for the heating system, a common return temperature that is lower than the dew point temperature of the flue gases, ensures more efficient heat exchange between those flue gases and the returning fluid. Embodiments of the invention recognise that it may be beneficial to balance a system using a target outlet temperature, rather than a target outlet flow rate per se.

100121 The fluid may be water.

100131 The outlet valve is preferably mechanically actuated.

100141 Advantageously, this means that the valve continues to function independent of an external power source, such as a battery, or the mains electricity supply. Not only does this make the valve more reliable, but also easier to install.

100151 The outlet valve may comprise a thermally responsive material. The outlet valve may comprise wax.

100161 The thermally responsive material preferably has beneficial physical properties in the temperature range of operation of the valve. The coefficient of thermal expansion of the thermally responsive material may also mean that the -4 -valve is able to respond to relatively small changes in water temperature.

100171 The radiator may further comprise an inlet valve connected to the inlet.

100181 The inlet valve may be used to directly control the amount of heat being supplied to radiator. The inlet valve may be a thermostatic radiator valve (TRV). The outlet valve may provide a cap on the maximum temperature of the fluid at the outlet, in which case, the inlet valve will be able to control the flow of fluid to reduce the heat input into the radiator. This is beneficial as the room temperature can be controlled by a user, relatively independently of the balancing function of the outlet valve.

100191 The predetermined target temperature may be predetermined based on a function of the boiler temperature (i.e. the boiler outlet temperature). The predetermined temperature may be between 5 and 25 degrees Celsius lower than the temperature of the fluid in the boiler. The predetermined temperature may be between 10 to 16 degrees Celsius lower than the temperature of the fluid in the boiler. This may ensure adequate heat is supplied to the radiators, while ensuring that the return temperature of the fluid is lower than the dew point temperature of the flue gases of the boiler, for efficient condensing heat exchange.

100201 The predetermined temperature may be predetermined based on a function of the temperature of the fluid at the inlet. The predetermined temperature may be between 10 and 20 degrees Celsius lower than the temperature of the fluid at the inlet. The predetermined temperature may be between 12 and 18 degrees Celsius lower than the temperature of the fluid at the inlet.

100211 The boiler is preferably a condensing boiler. A condensing boiler allows the heat in the flue gases, which are a by-product of the combustion of a fossil fuel, preferably gas, to be exchanged with the cooler water returning from the radiators of the heating system. At least some of the flue gases condense when exchanging heat, and at least some of the enthalpy of vaporisation of the flue gases is transferred into the return water, before it enters the boiler. This essentially pre-heats the cooler returning water, prior to being heated by the main boiler, which makes the system more energy efficient. Embodiments of the present invention tend to be especially beneficial with condensing boilers because achieving a consistent target return water temperature is especially beneficial when using a condensing boiler.

100221 According to a second aspect of the present invention, there is also provided a method of balancing a heating system. The heating system comprises a plurality of fluid filled radiators, each radiator comprising an inlet and an outlet. The method comprises a step of connecting an outlet valve to each outlet, each outlet valve being configured to respond to the temperature of the fluid at the outlet of each radiator. The method also comprises the step of controlling, with each outlet valve, the flow of fluid through the outlet to bring the temperature of the fluid at the outlet to a predetermined target temperature. Each outlet valve controls the flow of fluid such that there is a common outlet temperature for all of the radiators, thereby balancing the system and enabling a common boiler return temperature.

10023] Each outlet valve may comprise a thermally responsive material. The step of controlling the flow of fluid through the outlet may comprise the thermally responsive material -6 -responding to the temperature of the fluid at the outlet of each radiator.

100241 The step of controlling the flow of fluid through the outlet may comprise the thermally responsive material expanding in response to an increase in temperature.

100251 The expansion of the thermally responsive material may cause the flow rate of fluid through the outlet valve to reduce.

100261 The method may further comprise a step of pre-calibrating each outlet valve, prior to the step of connecting an outlet valve to each outlet.

100271 The step of pre-calibrating the outlet valve may be a function of a predetermined boiler fluid design temperature 100281 According to a third aspect of the present invention, there is also provided a kit of parts for balancing a heating system. The heating system comprises a plurality of radiators, each radiator comprising an inlet and an outlet, and a boiler fluidly connected to the plurality of radiators. The kit comprising a plurality of outlet valves, each outlet valve being configured to connect to each radiator outlet. Each outlet valve is configured to respond the temperature of the fluid at the outlet. Each outlet valve is also configured to control the flow of fluid through the outlet to bring the temperature of the fluid at the outlet to a predetermined target temperature. Each outlet valve is configured to control the flow of fluid through the outlet such that there is a common outlet temperature for all of the radiators, thereby balancing the system and providing a common boiler return temperature.

100291 The kit may further comprise a plurality of inlet valves, each inlet valve being configured to connect to each radiator inlet.

100301 It will of course be appreciated that features described in relation to one aspect of the present invention may be incorporated into other aspects of the present invention. For example, the method of the invention may incorporate any of the features described with reference to the apparatus of the invention and vice versa.

DESCRIPTION OF THE DRAWINGS

100311 Embodiments of the present invention will now be described by way of example only with reference to the accompanying schematic drawings of which: 100321 Figure 1 shows a schematic view of a heating system according to a first embodiment of the invention; 10033] Figure 2 shows a schematic view of a radiator according to the first embodiment of the invention; 10034] Figure 3 shows an outlet valve according to the first embodiment of the present invention; and 100351 Figure 4 shows a representation of a method of balancing a heating system according to a second embodiment of the present invention.

DETAILED DESCRIPTION

10036] The present invention will now be described herein by reference to the accompanying figures, wherein like reference numerals denote similar elements.

10037] Figure 1 shows a schematic view of a heating system 100 according to a first embodiment of the invention. The heating system 100 comprises a condensing boiler 150, connected to a number of zones 110, 120, 130 via a hot water pipe 154 that transports hot water from the boiler 150 to the zones, and a cold water return pipe 156, which brings cooler water back from the zones to the boiler so that it can be heated.

100381 Each zone has its own hot water supply pipe that branches off the hot water pipe 154. First zone 110 is supplied with hot water via first hot water supply pipe 151a. Second zone 120 is supplied with hot water via second hot water supply pipe 152a. An additional zones arrow 133 indicates that there may be any number of additional zones 130. There may be 5, 10, 15, or 20 additional zones for example, or any number 414 between.

100391 Since additional zone 130 is indicative that additional zones may be present, for the purposes of this embodiment it is assumed that only two zones are present. It will be understood that other embodiments can, of course, comprise more than two zones. The heating system 100 of the first embodiment comprises the first zone 110 and the second zone 120. Each zone 110, 120, comprises their respective water-filled radiators 111, 121. The first radiator 111 is supplied with hot water from the boiler 150 by the first hot water supply pipe 151a. The second radiator 121 is supplied with hot water from the boiler 150 by the second hot water supply pipe 152a. Heat-exchanged cooler water leaves the first radiator 111 through a first cold water return pipe 151b, to Joni the cold water return pipe 156. Heat exchanged cooler water leaves the second radiator 121 through a second cold water return pipe 152b, to join the cold water return pipe 156. The cold water return pipe 156 contains a mixture of water that flows from the first and second cold water return pipes 151b, 152b (and in embodiments, from further cold water return pipes 153b).

100401 The first radiator 111 comprises a heat exchanger 112.

The heat exchanger 112 facilitates the transfer of heat from the hot water within the heat exchanger 112 to the air within the room 110 -mostly via convection, and at least partially via radiation. The heat exchanger 112 has an inlet 112a, where hot water is fed into the hea7. exchanger 112, and an outlet 112b, where cooler, heat-exchanged, water exits the heat exchanger 112. Connected to the inlet 112a is a thermostatic radiator valve (TRV) 114. The:thermostatic radiator valve 114 is electrically powered and responds to the temperature of the zone 110 relative to a chosen temperature set-point. If the temperature of the zone 110 is lower than the set-point, the -calve 114 opens to Increase the inflow of hot water into the radiator, and if the temperature of the zone 110 is greater than the temperature set-point, the valve 114 closes/restricts the flow into the radiator.

pun Connected to the outlet 112b is an outlet valve 116.

The outlet valve 116 in the first embodiment of the invention is a balancing valve. The outlet valve 116 responds to the temperature of the water at the outlet 112b. The outlet valve 116 is pre-calibrated to provide a substantially constant water temperature at the outlet 112b. As the temperature of the water at the outlet 112b increases (as a result of an imbalance in the system for example), the outlet valve 116 restricts the flow, thereby reducing the flow rate and causing more heat to be exchanged in the heat exchanger 112, resulting in a lower temperature of water at the outlet 112b. This means that fluctuations in the temperature of the water at the inlet 112a can be corrected for, resulting in a substantially constant temperature of the water in at the outlet 112b.

100421 The second zone 120 also operates in a similar way to the first zone 110, such that the temperature of the water at -10 -the outlet 122b is controlled to be substantially the same as the temperature of the water at the outlet 112b. In this way, when the water in each of the first and second zone water return pipes is combined in the cold water return pipe 156, the temperature of the water in the cold water return pipe is substantially controlled to be a constant value (which is substantially the same as the temperature at each of the outlets 112b, 122b).

100431 As the boiler is a condensing boiler 150, the temperature of the water in the cold water return pipe 156 has an effect on the efficiency of the condensation. The temperature of the water in the cold water return pipe 156 is 50 degrees Celsius. The temperature of the water in the hot water pipe 154 is 65 degrees Celsius. The temperature of the water in the cold water return pipe 156 being 50 degrees Celsius is less than the dew point temperature of the flue gases of the boiler, such that the efficiency of the heat exchange in the boiler is greater.

100441 Figure 2 shows a schematic view of a radiator 111 according to the first embodiment of the invention.

100451 As previously described, the radiator 111 includes a heat exchanger 112 that has an inlet 112a and an outlet 112b. The heat exchanger 112 is designed to exchange heat from the hot water within the heat exchanger 112 to the surrounding air within the room/zone in which the radiator is situated. Connected to the inlet 112a is an inlet valve 114. The inlet valve 114 is a thermostatic radiator valve (TRV) 114. The TRV 114 is a known TRV and has a room/zone temperature set-point. If the temperature of the room/zone is below the set-point, then the TRV 114 opens to increase the flow rate of hot water into the heat exchanger 112. If the temperature of the room/zone is above the set-point, or is approaching close to the set-point, the TRV 114 closes to reduce the flow rate of hot water into the heat exchanger 112.

100461 There is an outlet valve 116 connected to the outlet 112b of the heat exchanger 112. The outlet valve 116 is a balancing valve 116. In contrast to known arrangements, the balancing valve 116 in the first embodiment has a predetermined outlet water temperature set-point. If the temperature of the water at the outlet 112b is greater than the predetermined temperature set-point, the balancing valve 116 restricts the flow of water at the outlet to reduce the flow rate, and therefore reduces the temperature of the water at the outlet 112b towards the predetermined temperature.

100471 If the temperature of the water at the outlet 112b is lower than the predetermined temperature set-point, then the balancing valve 116 opens to increase the flow rate, therefore increasing the temperature of the water at the outlet 112b towards the predetermined temperature.

100481 Figure 3 schematically shows an outlet valve 116 according to the first embodiment of the present invention.

100491 As shown in the previous figures, the outlet valve 116 (which is a balancing valve 116) is connected to the outlet 112b of a heat exchanger. Water leaving the valve 116 passes through the first cold water return pipe 151b, and into the cold water return pipe 156, which feeds back to the boiler 150. The outlet valve 116 includes a chamber containing a solid, thermally responsive, wax 117. Connected to the wax 117 is a piston 118 for adjusting the flow rate through the pipe 119.

100501 Valves of this structure per se are known, but their use as a balancing valve on an outlet of a radiator has not previously been suggested. As the temperature of the water flowing through the valve 116 Increases, the wax 117 expands, -12 -pushing the piston 118 upwards. As the piston 118 moves upwards, the flow of water is impeded. This Increases the residence time of the water in the heat exchanger, thereby reducing the temperature of the water at the outlet 112b. The response time of this mechanical valve 116 is typically quicker than the response time of a TRV, which has been found to be advantageous.

100511 As the temperature of the water flowing through the valve 116 decreases, the temperature of the valve 116 and the wax 117 decreases. The wax 117 thereby reduces in volume as a function of the temperature difference and its coefficient of thermal expansion. This causes the piston 118 to move downwards and increase the flowrate of the water. This reduces the residence time of the water in the heat exchanger, thereby increasing the temperature of the water at the outlet 112b.

100521 Figure 4 shows a representation of a method of balancing a heating system according to a second embodiment of the present invention. The heating system comprises at least two hot-water radiators. Each radiator has an inlet and an outlet.

100531 The method includes a step of connecting an outlet valve to each outlet 202. For example, if there are two zones, each comprising a hot-water radiator, then a total of two outlet valves will be needed. The connection of the outlet valve replaces what may already be a manual lockshield valve.

100541 Each outlet valve then responds to the temperature of the water at the outlet 204. The outlet valve responds to the temperature of the water at the outlet by comprising a thermally responsive material, which expands when its temperature is increased, and reduces in volume when its temperature decreases. The thermally responsive material is wax.

-13 - 100551 By using the response of the valve to the temperature of the water at the outlet, each outlet valve controls the flow of water through the outlet 206 (and through the valve). As the temperature of the water at the outlet increases, the -calve responds by decreasing the flow rate and controlling the temperature of the water at the outlet down towards a predetermined target temperature. As the temperature of the water at the outlet decreases, the valve responds by increasing the flow rate and controlling the temperature of the water at the outlet up towards the predetermined target temperature. Because each outlet valve performs this step, the temperature of the water at each outlet is substantially the same. The temperature of the water at each outlet being substantially the same means that the water temperature at each outlet is within a +/-two degree Celsius difference from each other. The water temperature at each outlet may be controlled to be within a +/-two degree temperature difference from the mean outlet temperature across all outlets. The water temperature at each outlet may be within a +/-one degree difference from each other. The water temperature at each outlet may be controlled to be within a +/-one degree temperature difference from the mean outlet temperature across all outlets.

10056] Having a common water temperature at each outlet thereby provides a common boiler return temperature, which is more efficient.

100571 The method as shown in Figure 4 also includes a step of pre-calibrating each outlet valve 200. The step of pre-calibrating each outlet valve 200 precedes the step of connecting an outlet valve to each outlet 202. The pre-calibration step includes pre-determining a target outlet temperature, and adjusting the outlet valve such that the -14 -water temperature at the outlet is corrected towards that temperature. The step of pre-calibrating each outlet valve includes an assessment of the heating requirements of the room/zone under design conditions, and the size of the radiator in that room/zone. The flowrate and hot water temperature drop can be calculated for design conditions, and the valve can be pre-calibrated to provide the required flowrates and temperature drop, for each individual, specific, room/zone. The pre-calibration 200 also takes into account the boiler design temperature (the required temperature drop is approximately the boiler design temperature less the target outlet temperature).

100581 Whilst the present invention has been described and illustrated with reference to particular embodiments, it will be appreciated by those of ordinary skill in the art that the invention lends itself to many different variations not specifically illustrated herein. By way of example only, certain possible variations will now be described.

100591 In embodiments of the present invention, the boiler is a condensing boiler. In other embodiments, the boiler may be a combi boiler, a system boiler, or a conventional boiler, which are terms that would be understood by the person skilled in the art. The boiler is preferably a condensing boiler. The boiler may be a gas boiler. The boiler may be an oil boiler, or an LPG boiler, or an electric boiler, or a biomass boiler.

100601 The term 'radiator' may refer to the 'heat exchanger', wherein the radiator has an inlet and an outlet. As such, the inlet and outlet valves are connected to the radiator inlet and outlet, rather than being comprised in the radiator. The term 'radiator' may therefore exclude the inlet and outlet valves, which may instead be connected to the radiator.

-15 - [0061] In embodiments of the present invention, the outlet valve may respond to the water temperature at the outlet by comprising a phase change material. The outlet valve may comprise a bimetallic strip. The outlet valve may be electrically powered. The outlet valve may be battery operated. The outlet valve may be supplied by electricity from the mains supply. The outlet valve may comprise a thermocouple, or a thermistor.

[0062] In embodiments of the present invention, while the outlet valve operates to bring the temperature of the water at the outlet to a target temperature, if the temperature of the water at the outlet is too low, the outlet valve will not be able to open further than maximum openness. In embodiments, the outlet valve provides a cap on the temperature of the water at the outlet. The outlet valve may prevent temperature of the water at the outlet from exceeding a threshold value.

[0063] It should be noted that throughout this specification, "or" should be interpreted as "and/or".

Claims

-16 -CLAIMS1. A heating system comprising: a plurality of fluid filled radiators, each radiator comprising an inlet and an outlet, with an outlet valve connected to the outlet; and a boiler fluidly connected to the plurality of radiators; wherein each outlet valve is configured to: respond the temperature of the fluid at the outlet; and control the flow of fluid through the outlet to bring the temperature of the fluid at the outlet to a predetermined target temperature, such that there is a common outlet temperature for all of the radiators, thereby balancing the system to enable a common boiler return temperature.
2. A heating system as claimed in claim 1, wherein the fluid is water.
3. A heating system as claimed in any preceding claim, wherein the outlet valve is mechanically actuated.
4. A heating system as claimed in claim 3, wherein the outlet valve comprises a thermally responsive material configured to mechanically actuate the outlet valve in response to a change in temperature of the fluid at the outlet.
5. A heating system as claimed in any preceding claim, wherein each radiator further comprises an inlet valve connected to the inlet.
6. A heating system as claimed in claim 5, wherein the inlet valve is a thermostatic radiator valve (TRV).
7. A heating system as claimed in any preceding claim, wherein the predetermined target temperature is between 10 to 16 degrees lower than the temperature of the fluid leaving the boiler.
8. A heating system as claimed in any preceding claim, wherein the boiler is a condensing boiler.
9. A method of balancing a heating system, the heating system comprising a plurality of fluid filled radiators, each radiator comprising an inlet and an outlet, the method comprising the steps of: connecting an outlet valve to each outlet, each outlet valve being configured to respond to the temperature of the fluid at the outlet of each radiator; and controlling, with each outlet valve, the flow of fluid through the outlet to bring the temperature of the fluid at the outlet to a predetermined target temperature, such that there is a common outlet temperature for all of the radiators, thereby balancing the system and enabling a common boiler return temperature.
10. A method as claimed in claim 9, wherein each outlet valve comprises a thermally responsive material, and wherein the step of controlling the flow of fluid through the outlet, comprises the thermally responsive material responding to the temperature of the fluid at the outlet of each radiator.
-18 - 11. A method as claimed in claim 10, wherein the step of controlling comprises the thermally responsive material expanding in response to an increase in temperature.
12. A method as claimed in any of claims 9 to 11, wherein the method further comprises a step of pre-calibrating each outlet valve, prior to the step of connecting an outlet valve to each outlet.
13. A method as claimed in claim 12, wherein the step of pre-calibrating the outlet valve is a function of a predetermined boiler fluid design temperature
14. A kit of parts for balancing a heating system, the heating system comprising a plurality of radiators, each radiator comprising an inlet and an outlet, and a boiler fluidly connected to the plurality of radiators, the kit comprising: a plurality of outlet valves, each outlet valve being configured to connect to each radiator outlet, wherein each outlet valve is configured to: respond the temperature of the fluid at the outlet; and control the flow of fluid through the outlet to bring the temperature of the fluid at the outlet to a predetermined target temperature, such that there is a common outlet temperature for all of the radiators, thereby balancing the system and providing a common boiler return temperature.
15. The kit as claimed in claim 14, wherein the kit further comprises a plurality of inlet valves, each inlet valve being configured to connect to each radiator inlet.